List of the Prior Art
The prior art appears to be best exemplified by the following patents:
______________________________________ Banczak 4,021,252 May 3, 1977 Wachtel 4,024,096 May 17, 1977 Parkinson 4,045,397 Aug. 30, 1977 Hwang 4,070,322 Jan. 24, 1978 Parkinson (Germany) October 28, 1976 ______________________________________